Find the Town Judge

Intuition

Solution

class Solution:
    def findJudge(self, N: int, trust: List[List[int]]) -> int:
        if N == 1:
            if trust == []:
                return 1
            return -1
        to = collections.Counter([i[1] for i in trust])
        judge = to.most_common(1)[0][0]
        trust_by = [False] * (N + 1)
        for i, j in trust:
            if i == judge:
                return -1
            if j == judge:
                trust_by[i] = True

        trust_by[judge] = True
        if not all(trust_by[1:]):
            return -1
        return judge